Why is '//' style multiline comment bad (in Java)?

Question

http://java.sun.com/docs/codeconv/html/CodeConventions.doc4.html#286

I was reading the above section of Java coding convention and started to wonder why it says \"// com

Answer 1

It makes modifying and formatting long comments extremely painful.

Most editors provide some sort of wrapping facility to automatically wrap text into lines of readable length. If every line starts with a '//' those will get moved around, then have to be deleted, and new ones re-inserted. All that tedious work can be avoided using '/* */ style comments.

Answer 2

Actually, I've been using // for multiple lines for years and never suffered any serious problem with it. I'm not a big fan of /*...*/ anymore because you get:

/* I'm commenting out all this code for a moment
  ...
  /* And here is a multi line comment
     that was hidden in the middle */
  ...
*/ 

Thank the compiler it gets upset and tells me of the problem.

Where as:

...
// And here is a multi line comment
// that was hidden in the middle
...

becomes with a single macro:

// ...
// // And here is a multi line comment
// // that was hidden in the middle
// ...

and is happily reversed with another single macro that returns it back to the original form

and as for:

  // but now you have 
  // trouble edditing
  // your comments so
  // that every  line
  // is of equal size

I say:

  // Tough, this is a piece of code not a 
  // published novel
  // and if varying lengths
  // make
  // it hard for you to read then heaven
  // forbid how you handle the code

And don't you just hate edditing:

/******************************************************************
 * Program: Foo.java                                              *
 ******************************************************************
 * Author:  Codey Art Work                                        *
 * Purpose: To do something with something and get something not  *
 *          forgetting something else.                            *
 ******************************************************************
 * Revision History:                                              *
 ******************************************************************
 *  Date  | Author |                                              *
 *--------|--------|----------------------------------------------*
 * 1/2/09 | Jack   | Now I have to keep all my comments in this   * 
 *        |        | tiny little space and if I edit it I just go *
 *        |        | aaarrrrrrggggggggggghhhhhhhhhhh!!!!!!!!!!!!! *
 ******************************************************************/

which always seem to appear in places insisting on /* */ over //

_{And I'd just like to say to the Stack Overflow guys, this is really cool editor. Doing code samples is so easy.}